1. Field of the Invention
The present invention relates to a substrate processing apparatus, a liquid film freezing method, and a substrate processing method using the liquid film freezing method which freeze a liquid film formed on a surface of a substrate including semiconductor wafers, glass substrates for photomask, glass substrates for liquid crystal display, glass substrates for plasma display, substrates for FED (field emission display), substrates for optical disks, substrates for magnetic disks, substrates for magnet-optical disks, etc.
2. Description of the Related Art
Conventionally used is a technique of freezing a liquid film as it is maintained adhering to a substrate surface by cooling a substrate as one of a substrate processing. Particularly this freezing technique is used as part of a substrate cleaning processing. That is, as devices typified by semiconductors have finer patterns, more advanced functions and higher precision, it becomes increasingly difficult to remove fine contaminants such as particles adhering to the substrate surface without destroying patterns formed on the substrate surface. And so, particles adhering to the substrate surface are removed in the following manner utilizing the freezing technique described above.
First, a liquid film is formed on a substrate surface by supplying liquid to the substrate surface. Subsequently, the liquid film is frozen by cooling the substrate. Thus, a frozen film is formed on the substrate surface to which particles adhere. Finally, the frozen film is removed from the substrate surface, whereby the particles are removed from the substrate surface together with the frozen film.
Here, the following liquid film freezing method may be used for freezing the liquid film formed on the substrate surface. In the apparatus described in JP-A-3-145130 for instance, a substrate is housed in a processing chamber and the substrate is supported on a pedestal (seating stage). A removal fluid such as steam and ultra pure vapor is then supplied to a surface of the substrate. This forms a liquid film of the removal fluid on the substrate surface. Following this, cooling gas whose temperature is lower than the freezing temperature of the removal fluid is introduced into the processing chamber so that the cooling gas circulates inside the processing chamber. This freezes the liquid film which is present on the substrate surface and forms a frozen layer (frozen film) all over the substrate surface.